when i read this i asume that this is the RS-232 protocol. so i should not know why this CAN'T be the RS-232 protocol
RS232 standard specify voltage levels, not a protocol. It is, however, the most abused name, I have even seen 485 called 232.

Anyhow, in that case, you can - using very short wires - connect p3 pins directly to the camera. Now you need find the baud rate, parity and stop bit requirements.

Erik